This application relates to a method of repairing a worn blade airfoil by securing additional material to the blade.
At least some known gas turbine engines include multiple sections, such as a fan, a compression section, a combustor section, a turbine section, and an exhaust nozzle. Blades are mounted within the compressor and turbine sections. The blades have airfoils extending from a platform toward a blade tip.
Rotating blades compress air in the compression section. The compressed air mixes with fuel and is combusted in the combustor section. Products of combustion expand to rotatably drive blades in the turbine section. Some blades rub against other portions of the engine when rotating. The engine dimensions are controlled to prevent too much rubbing, which can fracture the blade or bind the engine. Rubbing wears and stresses the blades, particularly near the blade tip.
Replacing an entire worn blade is expensive due to material and machining costs. Accordingly blades are often repaired instead of replaced. The repairs generally involve removing the worn blade tip and then building up weld filler or similar material on the blade. The material build-up is then machined to an appropriate airfoil shape to form a restored blade tip. Automated weld build-up on the blade can be difficult, especially since the blade has a curved airfoil profile and new material is only desired near the tip end of the blade. Vision systems are sometimes used to control a robotic arm that deposits weld material on the worn area of the blade. Applications using the robotic arm involve complex controls and vision systems, especially if the robotic arm tracks the curved airfoil profile of the blade. Manual weld processes are also used to deposit weld material on the worn area of the blade. Manual weld processes are often more inconsistent than automated processes.
Known cold metal transfer techniques are utilized for welding in various applications. However, cold metal transfer techniques have not been utilized to repair worn blades.